CVE-2025-5664: FreeFloat FTP Server Buffer Overflow Flaw

CVE-2025-5664 Overview

A critical buffer overflow vulnerability has been identified in FreeFloat FTP Server version 1.0 affecting the RESTART Command Handler component. This issue allows remote attackers to exploit improper memory buffer boundaries through manipulation of the RESTART command, potentially leading to arbitrary code execution or service disruption. The vulnerability has been publicly disclosed and exploit documentation is available.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability in the RESTART Command Handler to potentially execute arbitrary code or cause denial of service on affected FreeFloat FTP Server installations.

Affected Products

• FreeFloat FTP Server 1.0

Discovery Timeline

• June 5, 2025 - CVE-2025-5664 published to NVD
• June 24, 2025 - Last updated in NVD database

Technical Details for CVE-2025-5664

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The RESTART Command Handler in FreeFloat FTP Server 1.0 fails to properly validate input data, allowing attackers to overflow a memory buffer. When the RESTART command is processed, the application does not adequately check the length or content of user-supplied data before copying it into a fixed-size buffer, creating the conditions for a classic buffer overflow attack.

The vulnerability is network-accessible, requiring no authentication or user interaction to exploit. An attacker can connect to the FTP service and send a specially crafted RESTART command with excessive or malicious data to trigger the overflow condition.

Root Cause

The root cause lies in insufficient bounds checking within the RESTART command processing routine. The FreeFloat FTP Server does not validate the size of input parameters before memory operations, allowing attackers to write beyond allocated buffer boundaries. This lack of proper input validation is a fundamental secure coding oversight that enables memory corruption attacks.

Attack Vector

The attack can be initiated remotely over the network against any exposed FreeFloat FTP Server instance. An attacker would:

1. Establish a connection to the target FTP server on the default FTP port
2. Authenticate (if required) or exploit anonymous access
3. Send a maliciously crafted RESTART command with oversized or specially formatted data
4. The server processes the command without adequate bounds checking
5. Buffer overflow occurs, potentially allowing code execution or causing service crash

The exploitation technique involves sending carefully constructed payloads to the RESTART Command Handler to corrupt memory structures. Technical details and exploit documentation are available through the Fitoxs Exploit Documentation resource.

Detection Methods for CVE-2025-5664

Indicators of Compromise

• Abnormally long or malformed RESTART commands in FTP server logs
• FTP service crashes or unexpected restarts without administrative action
• Memory access violations or segmentation faults in FreeFloat FTP process
• Suspicious network connections to FTP ports followed by service instability

Detection Strategies

• Monitor FTP server logs for RESTART commands with unusually large parameters
• Deploy network intrusion detection signatures targeting buffer overflow patterns in FTP traffic
• Implement anomaly detection for FTP command lengths exceeding normal operational thresholds
• Use endpoint detection and response (EDR) solutions to monitor for memory corruption indicators

Monitoring Recommendations

• Enable verbose logging on FreeFloat FTP Server to capture all command inputs
• Configure alerts for FTP service crashes or unexpected process terminations
• Monitor network traffic to FTP ports for suspicious payload patterns
• Implement file integrity monitoring on FTP server binaries and configuration files

How to Mitigate CVE-2025-5664

Immediate Actions Required

• Disable the FreeFloat FTP Server service if not critically required for operations
• Restrict network access to the FTP server using firewall rules to trusted IP addresses only
• Consider migrating to an actively maintained and patched FTP server solution
• Implement network segmentation to isolate FTP services from critical network segments

Patch Information

No official vendor patch information is currently available for this vulnerability. FreeFloat FTP Server 1.0 appears to be legacy software without active maintenance. Organizations should consider replacing this software with a modern, actively supported FTP server solution.

Additional vulnerability details can be found at:

• VulDB Entry #311153
• VulDB CTI ID #311153

Workarounds

• Disable the RESTART command functionality if the FTP server supports command restriction
• Implement a Web Application Firewall (WAF) or network-level filter to block oversized FTP commands
• Use TCP wrappers or host-based firewall rules to limit connections to trusted clients only
• Run the FTP server in a containerized or sandboxed environment to limit exploitation impact
• Monitor and terminate connections exhibiting suspicious command patterns

# Configuration example - Firewall rules to restrict FTP access
# Allow FTP only from trusted networks
iptables -A INPUT -p tcp --dport 21 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 21 -j DROP